Poroid hidradenoma is a benign tumor that is classified as a poroid neoplasm, and is so called because of its morphology, which is intermediate between the cytological features of a poroid neoplasm (poroid and cuticular cells) and the architectural features of a hidradenoma (solid and cystic areas, and tumor cells restricted to the dermis). As these tumors are cystic and superficially located, fine needle aspiration cytology has been useful, but the diagnosis relies on the histological examination. A 79-year-old woman presented with a solitary walnut-sized, soft, tender, reddish-to-bluish nodular lesion that had been enlarging steadily over a period of two years. Histopathologic examination of the cutaneous lesion showed a well-demarcated tumor composed of poroid and cuticular cells in the dermis not connected to the overlying epidermis, consistent with poroid hidradenoma. Herein, we present a rare case of poroid hidradenoma arising in an unusual location. (Korean J Dermatol 2015;53(3):230∼234)